Niagara Escarpment

The Niagara Escarpment is a long escarpment, or cuesta, in Canada and the United States that starts from the south shore of Lake Ontario westward, circumscribes the top of the Great Lakes Basin running from New York through Ontario, Michigan, and Wisconsin.

It then follows the Georgian Bay shore northwestwards to form the spine of the Bruce Peninsula and Manitoulin Island, as well as several smaller islands in northern Lake Huron, where it turns westwards into the Upper Peninsula of northern Michigan, south of Sault Ste.

The escarpment's caprock is dolomitic limestone, also known as dolostone, which is more resistant and overlies weaker, more easily eroded shale as a weathering-resistant "cap".

It can also be seen at the three waterfalls of the Genesee River at Rochester (additional resistant rock layers make more than one escarpment in some places).

In Michigan, behind (south of) the escarpment, the cuesta capstone slopes gently to form a wide basin, the floor of an Ordovician-Silurian-age tropical sea.

There the constant deposition of minute shells and fragments of biologically-generated calcium carbonate, mixed with sediment washed in by erosion of the virtually lifeless landmasses, eventually formed a limestone layer.

During the Silurian period, some magnesium substituted for some of the calcium in the carbonates, slowly forming harder dolomite layers in the same fashion.

Highway 401, Canada's busiest, also crosses the Niagara Escarpment, beginning its long descent through rolling hills, farmland, and towns west of Milton.

High Cliff State Park in Wisconsin shows how modern and prehistoric humans used the escarpment for not only cultural reasons, but economic gains, as well.

A number of different animal and geometric effigy mounds and the remains of an early 20th-century limestone quarry and kiln are within the park.

[7] Some local organizations take their name from it, including The Ledgers, the sports teams at St. Mary's Springs Academy, which is perched on the side of the escarpment.

[10] Most of the region's vineyards lie upon the escarpment's eastern-facing slope that rises gently upward from the shores of Lake Michigan to the top of the Ledge, before dropping sharply off into Green Bay, and benefit greatly from constant air movement from Lake Michigan, which stores warmth during the summer.